extern vec2 stars[30];

vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords)
{
    float dist = 1000;
    for (int i = 0; i<30; i++) {
        dist = min(dist, pow(stars[i].x - screen_coords.x, 2) + pow(stars[i].y - screen_coords.y, 2));
    }
    return max(Texel(texture, texture_coords), vec4(1.0,1.0,1.0,1.0)/sqrt(dist));
}